In general, memory devices and communication devices include a signal processing device, and in the signal processing device, PRML read channel technology for extracting data information and its data recording timing information from a signal read out from, for example, an optical disc or the like, is commonly used. The PRML read channel technology relates to semiconductor devices in which analog circuitry and digital circuitry coexist, and has difficulty in correctly extracting timing information since the operating frequency of a digital circuit is increased year after year.
Conventionally, when timing information is extracted from an analog signal read out from a recording medium, a VCO (voltage control oscillator) is used to control a frequency and a phase, and a D/A converter (DAC) which is an analog circuit is used for a frequency and phase control signal (Patent Document 1). In Patent Document 2, the process performed by the analog circuit is replaced with a process performed by a digital circuit.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2002-8315    Patent Document 2: Japanese Unexamined Patent Application Publication No. H10-69727